The proliferation and morphological development of bone is known to be influenced by mechanical forces. A system has been developed to study the effects of mechanical stress on cells in tissue culture. The cells under study are cultured on polyether polyurethane or silicone rubber membranes. The membranes are then deformed by uniform hydrostatic pressure. Analysis of the membrane is made to determine the strain imparted to the cells. The pressure applied to the membrane is controlled by a fluidic control circuit which allows the investigator to vary the magnitude and time-varying nature of the strain imparted to the cells. A time-varying strain is employed because of the viscoelastic character of biological tissue.